The world reached an historic milestone November 15, 2022, when there were eight billion people on earth. By 2030, the world’s population is projected to be 8.5 billion.

Global fertility has fallen from an average five children per woman in the 1950s to 2.3 today. If fertility continues to decline, the global population may peak at 10.5 billion in the 2080s; two-thirds of the world’s people live in countries with a fertility rate below the replacement level of 2.1 children per woman.

Africa is projected to have 40 percent of the world’s population in 2100, almost four billion people, and half of the world’s people under 18. One result is likely to be some of the world’s largest cities. The 600 miles between Abidjan and Lagos is expected to be the largest African megalopolis, the term used to describe cities that share an economic space, as with the 50 million people in the 400-mile economic space between Washington DC and Boston.

By 2030, the Abidjan-Lagos megalopolis is expected to have 40 million people, and by 2100 could have 500 million people. African megalopolises tend to sprawl outward rather than upward, leading to massive traffic jams in the absence of public transportation. Algiers and Cairo are the only African cities with underground commuter lines. Developing cross-border cooperation between the five countries in the Abidjan-Lagos megalopolis has proven difficult. Ivory Coast, Benin and Togo are former French colonies whose elites speak French, while Nigeria and Ghana were British colonies.

Developing countries were buffeted in Fall 2022 by higher food, fertilizer and energy prices. Rising US interest rates accelerated the depreciation of developing country currencies and prompted capital outflows. Global economic growth slowed from almost six percent in 2021 to less than three percent in 2022, and could slow further in 2023, raising the specter of debt defaults.

Developing countries owe an estimated $200 billion to public and private creditors in rich countries, and dozens of countries may default if they are unable to restructure their external debts. China has extended $500 billion in loans, most to developing countries, and is more likely to extend payment periods than to forgive debt.